The present invention relates to an energy-saving type elevator control apparatus to which a secondary battery is employed.
FIG. 5 is a basic structural diagram showing a conventional elevator control apparatus to which a secondary battery is employed for controlling the elevator. In FIG. 5, reference numeral 1 denotes a three-phase A.C. power source, and reference numeral 2 denotes a converter constructed by diodes and the like for converting an A.C. power outputted from the three-phase A.C. power source 1 into a D.C. power. The D.C. power which has been obtained through the conversion in the converter 2 is supplied across D.C. buses 3.
In addition, reference numeral 4 denotes an inverter, which is controlled by a speed controller, as will be described later, for speed position control for the elevator. Thus, the inverter convert a direct current supplied through the D.C. buses 3 into an alternating current of a variable voltage and a variable frequency to supply the resultant alternating current to an A.C. motor (not shown) to rotate and drive a hoisting machine 5 of the elevator directly connected to the A.C. motor, thereby controlling ascending and descending of a car. A rope wound around the hoisting machine 5 is connected to the car and to a counter weight to allow a passenger in the car to move to a predetermined floor.
Here, the weights of the car and the counter weight are designed in such a way that they become roughly equal to each other when passengers one half the capacity get in the car. That is to say, in the case where the car is moved up and down with no load, the operation becomes a power running operation when the car is moved down, while becoming a regenerative operation when the car is moved up. Conversely, in the case where the car is moved down with the capacity load, the operation becomes the regenerative operation when the car is moved down, while becoming the power running operation when moving up the car.
In addition, reference numeral 6 denotes an elevator control circuit which is constructed by a microcomputer and the like, and which carries out the supervision/control of the whole elevator. Reference numeral 7 denotes a speed controller for carrying out the speed control of the elevator, reference numeral 8 denotes a charge/discharge control circuit, reference numeral 9 denotes a power accumulator provided across the D.C. buses 3 for accumulating therein a power during the regenerative operation of the elevator and for supplying the accumulated power to the inverter 4 together with the converter 2 during the powering operation, reference numeral 10 denotes a regenerative control circuit, reference numerals 11 and 12 respectively denote a regenerative control gate and a regenerative resistor which are connected across the D.C. buses 3, reference numeral 13 denotes a bus voltage measuring apparatus for measuring a bus voltage of the D.C. buses 3, and reference numeral 14 denotes a charging/discharging state measuring circuit for measuring a charging/discharging state of the power accumulator 9. The above-mentioned charge/discharge control circuit 8 controls the charge/discharge of the above-mentioned power accumulator 9 on the basis of a measured value from the bus voltage measuring apparatus 13 and a measured value from the above-mentioned charging/discharging state measuring circuit 14.
Here, the above-mentioned power accumulator 9, as in an example of a circuit shown in FIG. 6, is constructed by a secondary battery 90 of nickel-hydrogen or the like and a DC-DC converter for controlling charge/discharge of the secondary battery 90. The DC-DC converter includes a reactor 91, switching elements 92 and 93 such as IGBTs, and diodes 94 and 95 which are respectively connected in antiparallel with the switching elements 92 and 93. The charge for the secondary battery 90 is carried out with a step-down chopper circuit of the switching element 92 as the charge gate and the diode 95, while the discharge from the secondary battery 90 is carried out with a boosting type chopper circuit of the switching element 93 as the discharge gate and the diode 94. These gates are controlled by the charge/discharge control circuit 8.
In general, in order that the power accumulator 9 may be configured so as to be small and of low cost, the number of secondary battery 90 is reduced to be less, and hence the output voltage of the batteries is lower than the voltage across the D.C. buses 3. The voltage across the D.C. buses 3 is basically controlled so as to become near a voltage Vp which is obtained by rectifying the voltage of the three-phase A.C. power source 1. Thus, when charging the batteries with electricity, an input voltage to the power accumulator 9 needs to be decreased as a value lower than the voltage Vp down to the bus voltage, and also during the discharge, an output voltage of the power accumulator 9 needs to be increased or decreased as a value higher than the voltage Vp from or to the bus voltage. For this reason, the DC-DC converter is adopted.
In addition, a quantity exhibiting the degree of charge for the power accumulator 9 is called an SOC (state of charge), and this state of charge, SOC, is calculated on the basis of the difference between a quantity of charged current and a quantity of discharged current as described above. That is to say, a quantity of charged current is set plus, and a quantity of discharged current is set minus with the state of full charge of the power accumulator 9 as 100% to calculate the current SOC, i.e., a quantity of charge.
When the three-phase commercial power source 1 is in the state of a power failure, the operation of the elevator becomes possible through the power source supply from the power accumulator 9. In general, the secondary battery is used in the form in which sets of batteries each having about ten or less plural cells connected in series with one another are further connected in series with one another. However, if, for example, the number of series combinations of the secondary battery is selected so as to have the charge/discharge capability with which about one half the rated output of a motor depending on the speed and the load capacity of an elevator, then all of the regenerative powers can be charged since the regenerative power is about one half the rated electric power, and hence the maximum effect can be expected for the energy saving. In addition, at the time of a power failure, period of time (distance) during which the operation is possible is determined on the basis of a quantity Wh of power accumulated in the power accumulator 9. Conversely, if from the SOC in the normal running before a power failure to the SOC from start to finish of the discharge (here, the SOC from start to finish of the discharge means the SOC in which the discharge is possible in the range of not degrading batteries, and hence if the power is supplied in order to operate an elevator, then the terminal voltage of the secondary battery is abruptly decreased so that the desired power can not be supplied in some cases) is from 70% to 30% for example, in this case, when a quantity of power required to operate an elevator for a predetermined period of time in a power failure is 40% of the rated power, the number of series combinations of the secondary battery can be selected accordingly.
FIG. 7 is a flow chart showing the control for the charging gate and the discharging gate made by the charge/discharge control circuit 8. First of all, for example, the bus voltage is measured with the bus voltage measuring apparatus 13 (Step S1), and the measured voltage is compared with a desired voltage set value exhibiting the regenerative state (the desired voltage set value is equal to or smaller than a voltage set value which is set in the discharge control as will be described later, and is the value exhibiting the regenerative state which the D.C. bus voltage rises due to the regenerative power from a motor) to judge whether or not the measured voltage exceeds the voltage set value (Step S2).
If it is judged that the measured voltage does not exceed the set value, then it is judged that the operation of the elevator is the power running operation. Next, it is judged whether or not the measured value of a quantity of charge SOC of the secondary battery obtained with the charging/discharging state measuring circuit 14 exceeds a predetermined value (Step S3). If the measured quantity exceeds the set value, then the discharge control is started (Step S5). The set SOC in step S3, for example, is set to about 70%, and then a quantity of charge of the secondary battery is controlled so as to be held at 70%. In addition, in order to prevent the charge control start and the discharge control stop from being frequently repeated, the hysteresis of about 5% which can not be discharged off is held in one motion of the elevator, 75% is made the set SOC of the discharge control start, and 70% is made the set SOC of the discharge stop, which makes it possible to carry out the control with higher precision.
If it is judged in Step S2 that the measured voltage exceeds the set value, then it is judged that the operation of the elevator is the regenerative operation. Next, it is judged whether or not the measured value of the charge quantity SOC of the secondary battery obtained with the charging/discharging state measuring circuit 14 has exceeded an upper limit value exhibiting the limit of charge (Step S4). If the measured quantity exceeds the set value, then no charge control is carried out. If the measured quantity does not exceed the threshold, the charge control is started (Step S6). Here, the upper limit value exhibiting the limit of charge means the value in the range of about 80% to about 100% and means the upper limit value of over-charge which does not promote the degradation of the batteries.
FIG. 8 is a flow chart showing the control during the discharge made by the charge/discharge control circuit 8. While as the control system, the control having high stability for which the current control minor loop or the like is constructed in the voltage control may be carried out, in this case, the description will now be given with respect to the system for carrying out the control with the bus voltage for the sake of simplicity.
First of all, for example, the bus voltage is measured with the bus voltage measuring apparatus 13 (Step S11), and the measured voltage is compared with the desired voltage set value. Then, it is judged whether or not the measured voltage exceeds the voltage set value (Step S12). If the measured voltage does not exceed the set value, then it is judged whether or not the measured value of a discharge current of the secondary battery obtained with the charging/discharging state measuring circuit 14 has exceeded a predetermined value (Step S13).
From these judgements, when the measured voltage has exceeded the set value, or when even if the measured voltage has not exceeded the set value, the measured value of a discharge current of the secondary battery has exceeded a predetermined value, the adjustment time DT is subtracted from the current ON time to obtain new ON time in order to shorten the ON pulse width of the discharge gate (Step S14).
On the other hand, if it is judged in the above-mentioned Step S13 that the measured value of the discharge current of the secondary battery has not exceeded the predetermined value, the adjustment time DT is added to the current ON time to obtain new gate ON time in order to lengthen the ON pulse width of the discharge gate (Step S15). The ON control of the discharge gate is carried out on the basis of the gate ON time thus obtained, and also the resultant gate ON time is stored as the current ON time in a self-contained memory (Step S16).
In such a manner, lengthening the ON pulse width of the discharge gate increases the mean voltage as the output voltage of the power accumulator 9 and causes more current to flow through the buses from the secondary battery to increase the supply power and to increase the bus voltage across the D.C. buses 3 due to the power supply. When the power running operation is taken into consideration, the elevator requires the power supply and this power is provided from the discharge from the secondary battery and from the supply from the three-phase A.C. power source 1. If the bus voltage is controlled so as to get higher than the output voltage of the converter 2 based on the supply from the three-phase A.C. power source 1, then all of the powers are supplied from the secondary battery. However, the design is carried out in such a way that in order to construct the cost saving power accumulator, all of the powers are not supplied from the secondary battery, but are supplied at a suitable ration from the secondary battery and the three-phase A.C. power source 1.
That is to say, in FIG. 8, the measured value of the discharge current is compared with the current for partial charge of the supply (predetermined value). If the measured value of the discharge current exceeds the predetermined value, then the ON pulse width of the discharge gate is lengthened to further increase a quantity of supply, while if the measured value of the discharge current does not exceed the predetermined value, then the ON pulse width of the discharge gate is shortened, which results in that the power supply is clipped by carrying out that process repeatedly. If such a process is adopted, since of the power required for the inverter 4, the power supplied from the secondary battery is clipped, the bus voltage across the D.C. buses 3 is decreased, which results in that the power is started to be supplied from the converter 2. Since these processes are carried out for a very short period of time, practically, the voltage concerned settles to the suitable bus voltage to supply the power required for the elevator so that it becomes possible to supply the power at the desired ratio from the secondary battery 90 and the three-phase A.C. power source 1.
Next, the description will hereinbelow be given with respect to a flow chart during the charge control shown in FIG. 9.
When the regenerative power is supplied from an A.C. motor (not shown) for rotating and driving the hoisting machine 5, the bus voltage across the D.C. buses 3 is increased due to the supply of the regenerative power. When this voltage becomes higher than the output voltage of the converter 2, the power supply from the three-phase A.C. power source 1 is stopped. If this state continues when no power accumulator 9 is provided, while it is not illustrated because it is known, since the voltage across the D.C. buses 3 is increased, when the measured voltage value of the bus voltage across the D.C. buses 3 has reached a certain predetermined voltage, the regenerative control circuit 10 is operated to disable the regenerative control gate 11 constructed by a switching element or a contact.
As a result, the power is supplied to the regenerative resistor 12 and the regenerative power is consumed in the resistor and also the elevator is decelerated due to the electromagnetic braking effect. However, when the power accumulator 9 is provided, before the voltage concerned has been increased to the voltage at which the power is supplied to the regenerative resistor 12, the power accumulator 9 is charged with this regenerative power in accordance with the control made by the charge/discharge control circuit 8.
That is to say, as shown in FIG. 9, if the measured value of the bus voltage across the D.C. buses 3 obtained with the bus voltage measuring apparatus 13 exceeds the predetermined voltage, then the charge/discharge control circuit 8 detects that the state concerned is the regenerative state, and then lengthens the ON pulse width of the charge gate, thereby increasing the charge current to the secondary battery 90 (Steps S21-S22-S23). In a short time, the regenerative power from the elevator becomes less, and the voltage across the D.C. buses 3 is decreased accordingly so that the measured value obtained with the bus voltage measuring apparatus 13 does not to exceed the predetermined voltage, the control is carried out so as to shorten the ON pulse width of the charge gate and also the charge power is controlled so as to become less (Steps S21-S22-S24).
In such a manner, the bus voltage across the D.C. buses 3 is monitored to control the charge power, thereby controlling the bus voltage in the suitable range to carry out the charge. In addition, heretofore, the power consumed in the form of the regenerative power is accumulated to be reutilized, thereby realizing the energy saving. Thus, the current and voltage of the charge and discharge in the power accumulator 9 is usually controlled with the DC-DC converter, and the difference between the total of a quantity of charged current and the total of a quantity of discharged current becomes the charge quantity which currently remains in the power accumulator 9.
However, in the above-mentioned conventional elevator control apparatus, for continuation of the operation during a power failure of the commercial power source, it is necessary to supply the power, in addition to the driving power for the elevator, to a controller, and an illumination circuit. In addition, while for continuation of the service of the elevator, it is necessary to use effectively and usefully a quantity of charged power in the power accumulator 9, for example, if the power is supplied to all of the circuits during a power failure of the commercial power source, then there arises a problem in that before the elevator is moved to an objective floor of the passenger on board the car, the remaining power of a quantity of charged power in the power accumulator 9 is lost so that the elevator can not to be moved, and so forth. In addition, when the commercial power source is recovered, the operation of the elevator which has been restricted needs to be returned back to the original state.
The present invention has been made in order to solve the problems as described above, and therefore, it is an object of the present invention to obtain an elevator control apparatus which is capable of when a power failure of the commercial A.C. power source is detected, using effectively and usefully a quantity of charged power in a power accumulator and of when recovering the power supply, returning an elevator back to the original service to make the proper running possible.
In order to attain the above-mentioned object, according to the present invention, there is provided an elevator control apparatus, including: a converter for converting an A.C. power from an A.C. power source into a D.C. power through rectification; an inverter for converting the D.C. power from the converter into an A.C. power of a variable voltage and a variable frequency to drive an electric motor to operate the elevator; a power accumulator provided across D.C. buses between the converter and the inverter for accumulating therein a D.C. power from the D.C. buses in a regenerative operation of the elevator to supply the D.C. power accumulated in a powering operation to the D.C. buses; a charge/discharge control circuit for controlling the charge/discharge of the power accumulator for the D.C. buses; a charging/discharging state measuring circuit for measuring a quantity of charged power or a charging/discharging state of the power accumulator; a power failure detector for detecting a power failure of the A.C. power source; a control power supply device for supplying the power to the elevator control apparatus during a power failure; an illumination power supply device for supplying the power to an illumination circuit of the elevator during a power failure; and control means for, when a power failure is detected with the power failure detector, supplying the power of the power accumulator to the inverter and supplying the power to control circuits and the illumination circuit of the elevator with the charge/discharge control circuit to continue the operation of the elevator.
Further, the elevator control apparatus according to the present invention is characterized in that the control means, when a power failure is detected, limits speed of the elevator.
Further, the elevator control apparatus according to the present invention is characterized in that the control means, when a power failure is detected, selectively cuts off the illumination circuit of the elevator to limit the power supply in order to secure the necessary illumination and cut off a cable way to unnecessary illumination.
Further, the elevator control apparatus according to the present invention is characterized in that the control means, when a power failure is detected, selectively cuts off the control circuits of the elevator in order to secure only the control circuits of the control circuits required for the operation and cut off a cable way to the unnecessary control circuits.
Further, the elevator control apparatus according to the present invention is characterized in that the control means, after a power failure is detected, when the operation of the elevator is being continued, if a measured value obtained with the charging/discharging state measuring circuit has become equal to or smaller than a set value, or a predetermined period of time has elapsed, stops the operation of the elevator.
Further, the elevator control apparatus according the present invention is characterized in that the control means informs a passenger that the operation of the elevator will be stopped.
The elevator control apparatus according to the present invention further includes a power supply recovery detector for detecting power source recovery of the A.C. power source, and the system is characterized in that the control means, when power supply recovery is detected, returns speed of the elevator back to the original rated speed.
Further, the elevator control apparatus according the present invention is characterized in that the control means, when power supply recovery is detected, after the elevator is stopped if the elevator is being moved, returns the operation of the elevator from an operation mode at the time of a power failure to the normal operation mode to return speed thereof back to the original rated speed.
The elevator control apparatus according to the present invention further includes a power supply recovery detector for detecting power supply recovery of the A.C. power source, and the system is characterized in that the control means, when power supply recovery is detected, connects the control circuits or the illumination circuit which has been selectively cut off.
Further, the elevator control apparatus according to the present invention is characterized in that the control means is provided with both a continuous operation mode at the time of a power failure at which the operation of the elevator is continued, and a rescue operation mode at which the elevator is moved at low speed to be stopped at the nearest floor, and the control means selects the operation mode on the basis of a measured value obtained with the charging/discharging state measuring circuit or a lapse of a predetermined period of time from a power failure.
Further, the elevator control apparatus according to the present invention is characterized in that the control means selects the rescue operation mode on the basis of the measured value obtained with the charging/discharging state measuring circuit or a lapse of a predetermined period of time from a power failure to prevent the passenger from being shut in the elevator due to the insufficiency in quantity of charged power in the power accumulator.
Further, the elevator control apparatus according the present invention is characterized in that the control means, when the measured value obtained with the charging/discharging state measuring circuit becomes equal to or smaller than a first set value, or when a lapse of time from a power failure becomes equal to or larger than the first set value, does not receive the hall call so as not to allow getting-in of a new passenger and to carry out the service for the car call by the passenger currently on board, and when the measured value obtained with the charging/discharging state measuring circuit becomes equal to or smaller than a second set value, or when a lapse of time from a power failure becomes equal to or larger than the second set value, selects the rescue operation mode to prevent the passenger from being shut in the elevator due to insufficiency in quantity of charged power in the power accumulator.
Further, the elevator control apparatus according to the present invention is characterized in that the second set value of the quantity of charged power is equal to or smaller than the first set value, and the second set value for the elapsed time from a power failure is equal to or larger than the first set value.